[Establishment of highly metastatic human tumor cell line in nude mice]

A total of 22 adult nude mice (7 approximately 17 weeks old) of BALB/cA origin were inoculated subcutaneously (SC) with human tumor cell lines derived from rhabdomyosarcoma and lung carcinomas, including squamous cell carcinoma, bronchiolo-alveolar carcinoma, small cell carcinoma, giant cell carcinoma and 2 types of adenocarcinoma. 12 neoplasms (54.5%) was confirmed at the initial transplantation and 7 serially transplantable tumors were established in 201 nude mice. Metastatic behavior of 7 human tumor cell lines grown in nude mice was judged histologically after sacrifice and SC transplanted tumors could either be highly metastatic (giant cell carcinoma), moderately metastatic (adenocarcinoma PAb), poorly metastatic (squamous cell carcinoma and adenocarcinoma PAa) or non-metastatic (small cell carcinoma and bronchiolo-alveolar carcinoma). The tumor from SC inoculated giant cell carcinoma (PG) could produce regional and/or distant lymph node metastases (12/12) and lung metastases (9/12) in BALB/cA nude mice maintained under semi-barrier system conditions. Six NIH nude mice developed metastatic tumor nodules both in the lymph node and lung (6/6) under the same condition. The highly metastasizing property of PG transplanted tumors remained after passage for as many as 18 times. The limitations of nude mice as an in vivo model for the study of tumor biology are discussed, eg. malignant neoplasms rarely metastasize when transplanted into nude mice. The use of such model (PG) could lead to a better understanding of the biology of metastasis, thus contributing to the development of new approaches to the therapy of metastasis.